Project Summary/Abstract National data show that 82% of African American (AA) women are overweight or obese, and 57% are obese. The health risks associated with the high prevalence of overweight and obesity among AA women is concerning, as these risks contribute to subsequent chronicities including cardiovascular disease (CVD) and type 2 diabetes (T2D). Physical activity (PA) is an established mechanism to manage weight and to improve myriad cardiometabolic disease risk factors. However, despite these benefits, only 36% of AA women meet the national PA guidelines. The low PA levels among AA women coupled with the high prevalence of overweight/obesity and other chronic disease conditions indicate the need for effective strategies to promote sustained high PA in this high-risk population. Technology-based platforms (i.e. Smartphone applications, Internet, social media) represent potential channels to deliver PA interventions to AA women. However, few researchers have explored these platforms to deliver culturally relevant PA interventions to AA women. This represents a missed opportunity given the established success of technology-delivered behavior change interventions and data suggesting that AA women use Internet, social media, and Smartphones at equal or greater rates than other race/ethnic groups. Over the past 5 years, the applicant of this proposed work has focused on filling this gap in the published research through the development and evaluation of technology-based approaches to increase PA among AA women. Trained as a behavioral scientist, his graduate and postdoctoral training has been focused in the social and psychological sciences, with a particular emphasis on the development and evaluation of theory- driven, culturally relevant technology-based PA interventions for AA women. The research and training proposed in the current application will extend and refine the candidate's PA and health disparities research trajectory through : 1) focused training in the physiological and biochemical mechanisms underpinning cardiometabolic disease risk factors responsive to PA intervention, and 2) evaluation of the effects of a culturall relevant Smartphone-delivered PA program (Smart Walk) to improve (baseline to 6 months) and maintain (7 months to 12 months) higher PA levels among AA women and improve cardiometabolic disease risk factors. The candidate has identified a supportive and stimulating research environment at Arizona State University to pursue the proposed research. Under the mentorship and Drs. Barbara Ainsworth, Colleen Keller, Glenn Gaesser, and Sonia Vega-Lopez, he will gain the necessary skills to establish himself as an independent behavioral and health disparities research scientist. In the K99 portion of the grant award, the applicant will gan explicit training in the physiological and biochemical mechanisms underpinning cardiometabolic disease risk factors responsive to PA intervention through didactic coursework and hands-on clinical laboratory experience. Training in this research area will complement his already strong social science background by allowing him to gain a deeper understanding of the physiological mechanisms associated with the health-enhancing benefits of PA. In the R00 phase of the grant award, the applicant will deploy the training acquired during the K99 phase and build logically upon his previous health disparities research trajectory by implementing a 12-month technology-based PA randomized controlled trial to evaluate the effects of a culturally relevant Smartphone-delivered PA intervention to improve (baseline to 6 months) and maintain (7 months to 12 months) high PA levels and reduce cardiometabolic disease risk among obese AA women. Seventy-six obese AA women will receive either a culturally relevant, Social Cognitive Theory-based PA promotion program delivered using a Smartphone application or a wellness contact control condition. PA, fitness, and cardiometabolic disease risk factors will be evaluated. Potential physiological mechanisms through which PA may impact cardiometabolic disease risk factors will also be explored. The proposed research and training activities support the immediate and long-term career goals of the applicant. The applicant's immediate career goal is to enhance his theory based PA research to include salient mechanisms that underpin PA effects on health (i.e. inflammation), towards the prevention and treatment of cardiometabolic disease risk factors among AA women. His long-term career goals are to: a) establish an independent, externally-funded program of research focused on the identification of effective strategies to promote sustained PA among racial/ethnic minorities, and 2) reduce the disproportionate burden of the cardiometabolic diseases among high-risk minority populations. The training and research activities proposed in the current K99/R00 application will assist the candidate in achieving these career goals, and advance PA and health disparities science.